Work on a long anticipated project to improve Mission Avenue in downtown Oceanside began this week.

When the project is complete, the road — a main route from Interstate 5 to the ocean — will become a two-lane, one-way westbound street from Clementine Street to Coast Highway. To accommodate traffic heading the other way, nearby Seagaze Drive will become a one-way eastbound street.

The first phase of the work is on smaller Seagaze, where crews began blasting paint off the road on Thursday morning to make way for new road striping. The road was set to reopen Friday night as a one-way street from Coast Highway to Clementine.

The larger project will resume Nov. 12, when the conversion of Mission Avenue from a four-lane road to two lanes is scheduled to begin, said Nathan Mertz, Oceanside’s capital improvement project manager.

The overhaul is expected to cost about $2.5 million and take eight months to complete. Officials said Mission Avenue will not be closed entirely to traffic but some lanes will be blocked for some of work.

City officials say the project is key to revitalizing downtown. Plans to spruce up Mission Avenue have been in the works for years, but things stalled when the city’s redevelopment agency was dissolved as part of a plan to eliminate redevelopment programs statewide to help balance the state budget.

The project got back on track late last year thanks to a $1.5 million grant from the San Diego Association of Governments.

To make the road more pedestrian and bicycle friendly, the project includes back-in angled parking along Mission Avenue, broader sidewalks, canopy trees, benches, streetlights and bike racks.

“We are taking this main entrance and enhancing it,” Mertz said.

The city is taking steps to minimize disruption to businesses in the area, such as closing only sections of the street at a time. But merchants are understandably worried, said Rick Wright, executive director of MainStreet Oceanside.

“We knew that it was going to be very painful. It’s going to be extremely hard on the merchants on this avenue,” Wright said. “But the hope is that we can all pull together and create this beautiful entryway into the downtown.”

MainStreet Oceanside has been working with the city to host informational meetings to let business owners know what is going to happen, Wright said. Businesses will remain open during the work, he said.

The organization also distributed information via email and keeps maps of the project and other material on a table near its front entrance on Mission Avenue.

“The city has promised us that they will never close Mission completely during the entire project and they’re only going to do one side of the street at a time and one section of the street at a time,” he said. “We support the project but we want them to be sensitive to those of us who are on Mission Avenue.”

On Seagaze, the disruption was minimal.

Loren Leigh, owner of LLLReptile & Supply, said Thursday that apart from the noise outside he had not noticed any effect on his business. The pet store sells snakes, frogs, turtles and other animals.